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Help with 2015 kia optima ex

269 Views 9 Replies 6 Participants Last post by  sk8man, 
Alexm3290
I have a 2015 kia optima ex. A few months ago it started misfiring occasionally at idle, at redlights and such. Other then that no issues. So I changed the spark plugs and ignition coils (Bosch iridium spark plugs) & (TRQ ignition coils). Now the car has a rough idle in general. And drops down to about 500rpms every few minutes while at idle, and still has a more pronounced miss at red lights.
I gapped the spark plugs to .044 and this is the first time I've used trq but the coils seemed to be of fair quality. If anyone has had similar problem or any ideas? it would be great. Checking for vacuum leaks today later today
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Doolittle@K5
Chk MAP sensor
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bigbxsallday
When mine had similar symptoms it yielded a P0335 - crankshaft position sensor - needed to be replaced, made a huge difference, yet naturally read your odb2, may also have a pending code (no CEL on dash yet).

I do like to stick with OEM, from a local dealer, I've learned it makes a difference.
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Raybo
I don't know why posters can't list the mileage.

You don't gap iridium plugs they come gapped. Gapping them you may damage the tiny little iridium dot.

And go to the dealer and buy the factory sparkplug. Bosch plugs suck.

Your car needs a oil catch can its a GDI engine. It probably needs a carbon cleaning. Go on youtube and look up:

GDI ENGINE CLEANING
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Alexm3290
[email protected] said:
Chk MAP sensor
Click to expand...
Raybo said:
I don't know why posters can't list the mileage.

You don't gap iridium plugs they come gapped. Gapping them you may damage the tiny little iridium dot.

And go to the dealer and buy the factory sparkplug. Bosch plugs suck.

Your car needs a oil catch can its a GDI engine. It probably needs a carbon cleaning. Go on youtube and look up:

GDI ENGINE CLEANING
Click to expand...
Mileage is 95000 and I did in fact go get oem Denso spark plugs they were already pre gapped to .044 so I did not touch them. Made absolutely no difference even reinstalled the old coils to check that the new ones were good still no difference.
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T
Is the CEL on?
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Alexm3290
It's not throwing and codes on scan tool
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Alexm3290
Update
I also replaced pcv valve and did a crc treatment on it, and it's still got rough idle and I did a vacuum check the other day and it stayed green. the needle was alittle shakey. The rough idle is also more pronounced when ac is on.
My next things to check would be map sensor and air idle control valve. Unless anyone has any other ideas?
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Raybo
4
Its not running bad enough to launch a code probably not misfiring yet but its state of tune is not great. Or it may be in the early stages of oil loss. I would start watching the oil really closely and get a carbon cleaning treatment. I bet the oem plugs looked black and sooty.

What kind of engine oil are you using and whats the OCI?

Lots of info about carbon cleaning on youtube and on this site. A catch can is a must on this car. They sell a nice one on this K5 store on this site

Here's the K5 CC I installed on my 2017 its a very easy install you can use the existing mounting bolt:

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bigbxsallday said:
When mine had similar symptoms it yielded a P0335 - crankshaft position sensor - needed to be replaced, made a huge difference Top 12 Cheap Fast Cars to Buy In 2023 | Blog EpicVIN, yet naturally read your odb2, may also have a pending code (no CEL on dash yet).

I do like to stick with OEM, from a local dealer, I've learned it makes a difference.
Click to expand...
Have you bought the factory sparkplug?
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